A few years ago, was first recorded the receipt of electricity from a living plant. But now the investigation of a number of American, Dutch and Japanese scientists have come to a point where it became clear possibility of commercialization of bacterial fuel cells (BTE), powered by the waste products of plants.
Such BTE simultaneously generate electricity and reduce the greenhouse gas emissions.
American Ueyld Gordon, the inventor of Illinois, first discovered in 2006 that the metal nail driven into the wood and the metal wire connections is buried in the ground plate that acts as the anode, through which electrons rush to the plate-cathode. The theoretical explanation of this unusual fact given physicist Andreas Mershin of the Massachusetts Institute of Technology (USA) in the soil were more positively charged hydrogen ions than in the tree. In fact, the energy taken from the side effects of photosynthesis carried out by the tree. But for this to generate electricity is very little, and an independent source of energy such a "fuel cell" could be.
Bert Hamelers, a researcher from the University of Wageningen (Netherlands), approached the problem from the opposite side, and his work on this subject has recently appeared in the journal Bioresource Technology.
The training objective was to create a bacterial fuel cells, but not such as the present (for recycling and organic waste), and self-contained, requiring no systematic recharge. Mr. Hamelers wondered where you can find most of the bacteria, which are independent from the external fuel feed? This place was the soil. Soil bacteria are about 50% carbohydrate produced by plants during photosynthesis. Aerobic bacteria break down carbohydrates, formed with the hydrogen ions combine with oxygen, the result — a water molecule. Conclusion: Energy from aerobes not do.
Therefore, the researcher noted the anaerobic bacteria that live in the wetland soils, where there is no free oxygen. He was putting the electrodes in rows, sleeping space between them soaked small graphite grains that act as anode. After a series of experiments he and biotechnology David Strick was able to raise energy-conversion with 0.2 watts per square. m to 0.5 Watts. Mr. Strick was so inspired with the results, even founded Plant-e, with which hopes to commercialize the new bacterial fuel cells. Meanwhile, the efforts of Dutch scientists have been seen, and now they are in the EU program Plant Power, intending to raise the return to 3.2 watts per square. m and with half of that figure square meter grass roof (in Holland almost commonplace) can generate 14 kilowatt-hours a year, and from the roof of 50 m? — 700 kW • h, constituting 20% of the annual consumption of the average Dutch family.
As Strick and Hamelers going to get such results? First, there are plants in which the bulk of the mass is in the soil, where they identify up to 80% of the excess carbohydrates for themselves. Particularly attractive in this sense ordinary sugar beets. Another significant reserves remain bacterial flora. The existing natural flora decomposes carbohydrates so fast that the cathode does not have time to use the electrons in an oxidation reaction. Selection of other anaerobic flora, according to researchers, is able to significantly improve the energy-conversion. Themselves "power" can be located in any marsh, in areas that have no economic value. In contrast to existing wind and solar energy sources, bacteria are "working" at night — hence no need to deploy a network of expensive industrial energonakopiteley.
Similar ideas guided and Kazuya Watanabe, a biologist from the University of Tokyo (Japan). With electrodes in flooded rice paddies, he expects not only generate electricity but also reduce the impact of global warming.
As noted by Willie Germstrayt of the University of Ghent (Belgium), this initiative is particularly interesting because the flooded rice fields produce up to 20% of the annual emissions of methane — one of the most powerful greenhouse gases. In fact, all the hydrogen ions that soil bacterial fuel cells oxidize in obtaining electricity, used to take on the oxidation of the "fragments" of carbohydrate molecules and led to the development of methane, then fall out of the soil into the air. BTE reduce methane emissions, regardless of the type of plants, but the rice fields in Asia occupy a large area (in Japan it is 12% of the country), and at the same time because of the water cut them live only anaerobic bacteria, particularly vigorously producing methane.
In short, the authors of the new fuel cell on hand already have significant environmental advantages. Will they run of economic success and power, time will tell.